Covering member, fabric material-reinforcing structure, and sport shoe including same

ABSTRACT

A covering member is provided in a portion of an upper of a shoe. The covering member includes: a fabric material comprised of a stretchable mesh fabric; and an overlay material made of an olefin-based thermoplastic elastomer and integrally provided on a surface of the fabric material. A direction intersecting with a stretch direction of the fabric material is defined as a width direction. The covering member has such strain rate dependence that a tensile load per unit width with respect to a strain amount of the covering member is higher and the covering member is less stretchable when a strain rate of the upper in the stretch direction of the fabric material is in a high strain rate region than when the strain rate of the upper is in a low strain rate region.

TECHNICAL FIELD

The present invention relates to a covering member, a fabric material-reinforcing structure, and a sport shoe including the same.

BACKGROUND ART

Shoes including an upper for covering the instep of a foot have been known from Patent Document 1, for example. This upper includes a mesh material having meshes and a reinforcement part sewn on the mesh material at a position corresponding to a tiptoe area of the foot. The reinforcement part is made of a material that is difficult to stretch, such as artificial leather, and is designed for maintaining the shape of a partial region of the upper (for example, a portion corresponding to a front portion of a foot including the toes).

CITATION LIST Patent Documents

Patent Document 1: International Publication No. 2008/047659

SUMMARY OF THE INVENTION Technical Problem

Meanwhile, it is generally desirable, for sport shoes or the like, that for example, the upper has such fitting properties that it fits with the shape of a foot of a user when the user puts on the shoe, whereas the upper has such holding properties that it firmly covers and holds the user's foot when the user does heavy exercise.

However, the known shoes as disclosed in Patent Document 1 have a problem: the upper having the reinforcement part that is difficult to stretch firmly covers and holds a user's foot, while the upper is difficult to stretch and to fit with the shape of the user's foot when the user puts on the shoes. Specifically, the shoes of Patent Document 1 merely exhibit its holding properties when the user wearing the shoes does heavy exercise and a sudden external force is applied to the uppers. Unfortunately, when a gentle external force is applied to the uppers in a situation where the user puts on the shoes, for example, the fitting properties that are generally needed are impaired. Thus, it is difficult for the shoe structure of the known art to exhibit both the fitting properties and the holding properties according to a state of usage.

In view of the foregoing background, it is therefore an object of the present invention to enable a covering member or a fabric material-reinforcing structure to have both fitting properties and holding properties and to exhibit the fitting or holding properties according to a state of usage.

Solution to the Problem

In order to achieve the above object, a covering member or a fabric material-reinforcing structure of the present invention is configured such that it becomes flexible when a strain rate is low and it becomes hard when the strain rate is high.

Specifically, a first aspect of the present invention is directed to a covering member for covering a body. The covering member includes a stretchable fabric material and an overlay material made of a thermoplastic elastomer and integrally provided on a surface of the fabric material. A direction intersecting with a stretch direction of the fabric material is defined as a width direction, a strain rate region with strain rates higher than a reference strain rate is defined as a high strain rate region, and a strain rate region with strain rates equal to or lower than the reference strain rate is defined as a low strain rate region. The covering member has such strain rate dependence that a tensile load per unit width with respect to a strain amount of the covering member is higher and the covering member is less stretchable when a strain rate of the covering member in the stretch direction of the fabric material is in the high strain rate region than when the strain rate of the covering member is in the low strain rate region.

According to the first aspect, the covering member, which is formed by integrally providing the overlay material made of a thermoplastic elastomer on a surface of the fabric material, has such strain rate dependence that the tensile load per unit width with respect to the strain amount is higher and the covering member is less stretchable in the high strain rate region than in the low strain rate region. That is, the covering member has such characteristics that it is flexible and easy to stretch in the low strain rate region while it is harder and less stretchable in the high strain rate region than in the low strain rate region. Thanks to the characteristics, when a gentle external force is applied to the covering member (that is, the strain rate is in the low strain rate region), such as when a user puts on the covering member, the covering member is relatively flexible and easy to stretch. Thus, the covering member has improved fitting properties and fits the shape of a body. On the other hand, when the user wearing the covering member does heavy exercise and a sudden external force is applied to the covering member (that is, when the strain rate is in the high strain rate region), the covering member is relatively hard and less stretchable. Thus, the covering member has improved holding properties and firmly holds the body covered with the covering member. Thus, the covering member of the first aspect has both the fitting properties and the holding properties described above, and exhibits the fitting or holding properties according to a state of usage. Note that the “tensile load per unit width” refers to the value of a tensile load (N/mm) applied to a unit width, where a direction intersecting with the stretch direction of the fabric material is defined as the width direction and a dimension of the covering member in the width direction is converted to the unit width of 1 mm.

A second aspect of the present invention is an embodiment of the first aspect. In the second aspect, the overlay material is bonded to the surface of the fabric material via an extensible thermoplastic film material.

According to the second aspect, the overlay material and the surface of the fabric material can be bonded to each other, while the thermoplastic film material separates them from each other and substantially prevents part of the thermoplastic elastomer from permeating the fabric material. This makes it possible to prevent the stretchability of the covering member from being impaired, while keeping the fabric material and the overlay material firmly bonded to each other.

A third aspect of the present invention is an embodiment of the first or second aspect. In the third aspect, a relationship between the strain and the tensile load per unit width determined by a tensile test is that the tensile load P per unit width (N/mm) with respect to a strain amount of 1% is within the range of 0.05≤P≤1.09 in the low strain rate region, whereas the tensile load P is within the range of 0.65≤P≤2.47 in the high strain rate region.

According to the third aspect, setting the tensile load per unit width with respect to a strain amount of 1% within the respective numerical range can specifically achieve the covering member having such strain rate dependence that the covering member is flexible and easy to stretch in the low strain rate region whereas it is harder and less stretchable in the high strain rate region than in the low strain rate region.

A fourth aspect of the present invention is an embodiment of any one of the first to third aspects. In the fourth aspect, a relationship between the strain and the tensile load per unit width determined by a tensile test is that the tensile load P per unit width (N/mm) with respect to a strain amount of 5% is within the range of 0.25≤P≤2.05 in the low strain rate region, whereas the tensile load P is within the range of 1.72≤P≤7.85 in the high strain rate region.

According to the fourth aspect, setting the tensile load per unit width with respect to a strain amount of 5% within the respective numerical range can specifically achieve the covering member having such strain rate dependence that the covering member is flexible and easy to stretch in the low strain rate region, whereas it is harder and less stretchable in the high strain rate region than in the low strain rate region.

A fifth aspect of the present invention is directed to a covering member for covering a body, the covering member including: a stretchable fabric material; and an overlay material made of a thermoplastic elastomer and integrally provided on a surface of the fabric material. The covering member has such strain rate dependence that as a strain rate of the covering member in a stretch direction of the fabric material increases, a tensile load per unit width with respect to a strain amount increases and the covering member becomes less stretchable.

Just like the first aspect, the fifth aspect can have both the fitting properties and the holding properties and exhibit the fitting or holding properties according to a state of usage.

A sixth aspect of the present invention is directed to a sport shoe including an upper having the covering member of any one of the first to fifth aspects.

According to the sixth aspect, thanks to the strain rate dependence of the covering member, when a gentle external force is applied to the upper (that is, when the strain rate is in the low strain rate region), such as when a user puts on the sport shoes, the upper is relatively flexible and easy to stretch. Thus, the user is allowed to put on the sport shoes smoothly, and the sport shoes suitably fit the shapes of the user's feet, exhibiting good fitting properties. On the other hand, when the user wearing the sport shoes does heavy exercise and a sudden external force is applied to the upper (that is, when the strain rate is in the high strain rate region), the upper is relatively hard and less stretchable. Thus, the shoes firmly hold the user's feet covered with the the upper, exhibiting good holding properties.

A seventh aspect of the present invention is directed a fabric material-reinforcing structure including: a stretchable fabric material; and a reinforcing material made of a thermoplastic elastomer, integrally provided on the fabric material, and reinforcing a mechanical strength of the fabric material. A direction intersecting with a stretch direction of the fabric material is defined as a width direction, a strain rate region with strain rates higher than a reference strain rate is defined as a high strain rate region, and a strain rate region with strain rates equal to or lower than the reference strain rate is defined as a low strain rate region. The fabric material-reinforcing structure has such strain rate dependence that a tensile load per unit width with respect to a strain amount of the fabric material-reinforcing structure is higher and the fabric material-reinforcing structure is less stretchable when a strain rate of the fabric material-reinforcing structure in the stretch direction of the fabric material is in the high strain rate region than when the strain rate of the fabric material-reinforcing structure is in the low strain rate region.

The seventh aspect provides the same advantages as in the first aspect. Further, according to the seventh aspect, the reinforcing material maintains the mechanical strength of the fabric material constant, making it possible to reduce age deterioration of the fabric material, for example.

An eighth aspect of the present invention is an embodiment of the seventh aspect. In the eight aspect, the reinforcing material is bonded to the surface of the fabric material via an extensible thermoplastic film material.

The eighth aspect provides the same advantages as of the second aspect.

A ninth aspect is an embodiment of the seventh or eighth aspect. In the ninth aspect, a relationship between the strain and the tensile load per unit width determined by a tensile test is that the tensile load P per unit width (N/mm) with respect to a strain amount of 1% is within the range of 0.05≤P≤1.09 in the low strain rate region, whereas the tensile load P is within the range of 0.65≤P≤2.47 in the high strain rate region.

The ninth aspect provides the same advantages as of the third aspect.

A tenth aspect of the present invention is an embodiment of any one of the seventh to ninth aspects. In the tenth aspect, a relationship between the strain and the tensile load per unit width determined by a tensile test is that the tensile load P per unit width (N/mm) with respect to a strain amount of 5% is within the range of 0.25≤P≤2.05 in the low strain rate region, whereas the tensile load P is within the range of 1.72≤P≤7.85 in the high strain rate region.

The tenth aspect provides the same advantages as of the fourth aspect.

An eleventh aspect of the present invention is directed to a fabric material-reinforcing structure comprising: a stretchable fabric material; and a reinforcing material made of a thermoplastic elastomer, integrally provided on the fabric material, and reinforcing a mechanical strength of the fabric material. The fabric material-reinforcing structure has such strain rate dependence that as a strain rate of the fabric material-reinforcing structure in the stretch direction of the fabric material increases, a tensile load per unit width with respect to the strain amount increases and the fabric material-reinforcing structure becomes less stretchable.

The eleventh aspect provides the same advantages as of the fifth aspect.

A twelfth aspect of the present invention is directed to a sport shoe including an upper including the fabric material-reinforcing structure of any one of the seventh to eleventh aspects.

The twelfth aspect provides the same advantages as of the sixth aspect.

Advantages of the Invention

As can be seen from the foregoing description, the covering member or the fabric material-reinforcing structure of the present invention, which has such characteristics (i.e., strain rate dependence) that it is flexible and easy to stretch in the low strain rate region and is harder and less stretchable in the high strain rate region than in the low strain rate region, exhibits high fitting properties in the low strain rate region, and high holding properties in the high strain rate region.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a shoe according to a first embodiment of the present invention.

FIG. 2 is a plan view of the shoe according to the first embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view showing the structure of a covering member used in an upper of a shoe.

FIG. 4 is a plan view schematically showing a positional relationship between an overlay material and the skeleton structure of a foot.

FIG. 5 is a side view schematically showing a positional relationship between the overlay material and the skeleton structure of a foot.

FIG. 6 is a graph showing the results (stress-strain characteristics) of a tensile test on a sample p1.

FIG. 7 is a graph showing the results (stress-strain characteristics) of a tensile test on a sample e3.

FIG. 8 schematically shows the shape of each sample.

FIG. 9 is a graph showing the results (a relationship between strain and a tensile load per unit width) of a tensile test on Sample 4.

FIG. 10 is a graph showing the results (a relationship between strain and a tensile load per unit width) of a tensile test on Sample 5.

FIG. 11 is a graph showing the results (a relationship between strain and a tensile load per unit width) of a tensile test on Sample 6.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will now be described in detail with reference to the drawings. Note that the following description of the embodiments is merely an example in nature, and is not intended to limit the scope, application, or uses of the present invention.

FIGS. 1 to 5 show a shoe S according to an embodiment of the present invention, which is preferably used as a shoe for indoor sports (e.g., volleyball, badminton, etc.) in which a player makes sudden movements particularly frequently. In the drawings, only the right shoe of a pair of shoes S is shown as an example. Since the left shoe is symmetrical to the right shoe S, only the right shoe S will be described in the following description, and the description of the left shoe will be omitted herein. In the following description, the expressions “above,” “upward,” “on a/the top of,” “below,” “under,” and “downward,” represent the vertical positional relationship between respective components of the shoe S. The expressions “front,” “fore,” “forward,” “anterior,” “rear,” “hind,” “behind,” “backward,” and “posterior” represent the positional relationship in the longitudinal direction between respective components of the shoe S. The expressions “left (side),” “leftward,” “right (side),” and “rightward” represent the positional relationship in the width direction of the shoe S.

As shown in FIG. 1, the shoe S includes an outsole 1 which includes a ground surface configured to contact the ground. The outsole 1 is made of a hard elastic member having a high hardness. A midsole 2 configured to support a planta of a human body is provided above the outsole 1. The midsole 2 is made of, for example, a soft elastic material, and has a lower portion bonded to an upper portion of the outsole 1 with an adhesive or the like.

Above the midsole 2, an upper 3 is provided to cover a foot of a body (specifically, from the tiptoe to the heel). The upper 3 has an ankle opening 3 a in its top portion. The lower periphery of the upper 3 is integrally bonded to the entire periphery of the midsole 2 with an adhesive or the like. The shoe S has, in its top portion, a throat opening 3 b which is continuous with the ankle opening 3 a and extends in the longitudinal direction. Left and right eyelet tapes 3 c are fixed to the left and right edges of the throat opening 3 b by sewing or other means.

The upper 3 includes a stretchable fabric material 4. As the fabric material 4, a mesh fabric having meshes and produced by warp-knitting (i.e., double-raschel knitting) a polyester yarn may be suitably used, for example. Such a mesh fabric is characterized in that the fabric itself tends to become more flexible as the diameter of the yarn decreases or as the stitches become coarser. In addition, it is possible to produce a flexible mesh fabric by reducing the thickness of the fabric. That is, a strain rate dependence of the upper, which will be described later, can be adjusted by appropriately changing the degree of stretch of the mesh fabric. In this embodiment, the fabric material 4 is configured to stretch in the width direction of the shoe S.

As shown in FIGS. 1 and 2, band-shaped overlay materials 5, 5, . . . which are made of a thermoplastic elastomer are integrally provided on portions of the surface of the fabric material 4. Specifically, as shown in FIG. 3, the overlay material 5 is bonded to (i.e., combined with) the surface of the fabric material 4 via an extensible thermoplastic film material 6 (i.e., a hot-melt adhesive). In this embodiment, the overlay material 5 and the portion of the fabric material 4 to which the overlay material 5 is bonded together form a covering member 7 of the present invention. The thickness of the overlay material 5 is preferably within the range from 0.5 mm to 2.0 mm.

As shown in FIGS. 1 and 2, a pair of overlay materials 5, 5 are arranged along the shoe width in a front portion of the shoe S and another pair of overlay materials 5, 5 are arranged along the shoe width in a rear portion of the shoe S. In side view, each overlay material 5 extends in an inverted V shape between the eyelet tape 3 c and the midsole 2. As shown in FIGS. 4 and 5, the pair of overlay materials 5, 5 in the front portion of the shoe S is arranged to correspond to, for example, a forefoot F (specifically, a part including front end portions of the metatarsals, the proximal phalanxes, and the distal phalanxes) of a foot. The other pair of overlay materials 5, 5 in the rear portion of the shoe S is arranged to correspond to, for example, a part including a midfoot M and a front portion of a hindfoot H (specifically, a part including rear end portions of the metatarsals, the cuneiform bone, the cuboid bone, and the navicular bone).

It is preferable to use, as the thermoplastic elastomer for the present invention, an elastomer having such physical properties that a value (so-called tan s) obtained by dividing a coefficient of viscosity by a coefficient of elasticity exhibits a peak value in the room temperature range. A thermoplastic elastomer having such physical properties is likely to exhibit strain rate dependence similar to that which will be described later. More specifically, the thermoplastic elastomer used in this embodiment is comprised of a composition containing a 4-methyl-1-pentene/α-olefin copolymer (manufactured by Mitsui Chemicals, Inc.). A thermoplastic elastomer containing this composition or any other similar composition can be configured such that the tan s reaches the peak value in the room temperature range and the hardness of the thermoplastic elastomer has a practical value suitable for this embodiment, by adjusting the blend amount of an olefin polymer component such as polypropylene (PP) and the blend amount of an olefin rubber component such as ethylene propylene rubber (EPR) and ethylene propylene diene rubber (EPDM). Other specific examples of the thermoplastic elastomer include olefin-based thermoplastic elastomers, urethane-based thermoplastic elastomers, and styrene-based thermoplastic elastomers. In particular, to reduce the weight of the overlay material 5, an olefin-based thermoplastic elastomer is more preferable.

Next, the present invention has a feature: the covering member 7 of the upper 3 has such strain rate dependence that as the upper 3 increases in its strain rate in the stretch direction of the fabric material 4 serving as a base, a tensile load per unit width with respect to a strain amount increases and the covering member 7 becomes less stretchable. Specifically, the covering member 7 has such strain rate dependence that a tensile load per unit width with respect to a strain amount of the covering member 7 is higher and the covering member 7 is less stretchable when a strain rate of the upper 3 in the stretch direction of the fabric material 4 is in a high strain rate region with strain rates above a reference strain rate than when the strain rate of the upper 3 is in a low strain rate region with strain rates at or below the reference strain rate.

Here, the “tensile load per unit width” refers to the value of a tensile load (N/mm) applied to a unit width, where a direction intersecting with the stretch direction of the fabric material 4 is defined as the width direction and a dimension of the covering member 7 in the width direction is converted to the unit width of 1 mm. More specifically, it is general to determine the strain rate dependence based on a change in tensile stress with respect to stain amount. However, in this embodiment, in view of the fact that the covering member 7 is unlikely to have a strictly uniform thickness due to its combined structure including the fabric material 4 and the overlay material 5, the concept of “tensile load per unit width” is employed to determine the strain rate dependence of the covering member 7, instead of the concept of stress described as a force per unit cross-sectional area (N/mm²).

For the sake of convenience in describing this embodiment, as an example, a strain rate of, for example, 100%/s is defined as the “reference strain rate”, and a strain rate region with strain rates equal to or lower than the reference strain rate (e.g., a strain rate region from 4.2%/s to 100%/s) is defined as a “low strain rate region,” while a strain rate region with strain rates higher than the reference strain rate (e.g., a strain rate region less than or equal to 500%/s and higher than 100%/s) is defined as a “high strain rate region.”

As can be seen form foregoing, in the shoe S according to this embodiment, the covering member 7 that is provided for the upper 3 and comprised of the overlay material 5 made of the thermoplastic elastomer and integrated with the surface of the fabric material 4 has strain rate dependence described above. As a result, specifically, the covering member 7 has such characteristics that in the low strain rate region, it is relatively flexible and easy to stretch, whereas it is harder and less stretchable in the high strain rate region than in the low strain rate region. Thanks to the characteristics, when a gentle external force is applied to the upper 3 (i.e., when the strain rate is in the low strain rate region), such as when a user puts on the shoes S, the upper 3 is relatively flexible and easy to stretch. Consequently, the user is allowed to smoothly insert his/her foot into the ankle opening 3 a to put on the shoe S, and the shoe S suitably fits the shape of the user's foot, exhibiting a good fitting property. On the other hand, when the user wearing the shoes S does heavy exercise and a sudden external force is applied to the upper 3 (i.e., when the strain rate is in the high strain rate region), the upper 3 is relatively hard and less stretchable. Thus, the shoe S firmly holds the user's foot covered with the upper 3, exhibiting high holding properties. Thus, this embodiment enables the upper 3 to have both the holding property and the fitting property described above, and to exhibit the fitting or holding properties according to a state of usage.

The overlay material 5 of the covering member 7 is bonded to the surface of the fabric material 4 via the extensible thermoplastic film material 6. Thanks to this configuration, the overlay material 5 and the surface of the fabric material 4 can be bonded to each other, while the thermoplastic film material 6 separates them from each other and substantially prevents part of the thermoplastic elastomer from permeating the fabric material 4. This makes it possible to prevent the stretchability of the upper 3 from being impaired, while keeping the fabric material 4 and the overlay material 5 firmly bonded to each other.

For the covering member 7, strain and a tensile load per unit width determined by a tensile test preferably have the following relationship: in the low strain rate region, the tensile load P per unit width (N/mm) with respect to a strain amount of 1% is within the range of 0.05≤P≤1.09, whereas in the high strain rate region, the tensile load P is within the range of 0.65≤P≤2.47. Alternatively, strain and the tensile load per unit width determined by the same tensile test preferably have the following relationship: in the low strain rate region, the tensile load P per unit width (N/mm) with respect to a strain amount of 5% is within the range of 0.25≤P≤2.05, whereas in the high strain rate region, the tensile load P is within the range of 1.72≤P≤7.85. Thus, setting the tensile load P per unit width with respect to a strain amount of 1% and/or 5% within the respective numerical range described above enables the covering member 7 of the upper 3 to have such strain rate dependence that the covering member 7 is flexible and easy to stretch in the low strain rate region, while the covering member 7 is harder and less stretchable in the high strain rate region than in the low strain rate region. In particular, the numerical value of a strain amount of 5% is considered to be the average of strain amounts generated when an external force is applied to the uppers provided for sport shoes of the known art. Thus, configuring the covering member 7 of the upper 3 such that the tensile load per unit width with respect to a strain amount of 5% is within the numerical range described above further ensures that both the fitting properties and the holding properties are obtained.

Variation of Embodiment

The shoe S of the embodiment described above includes the covering member 7 including the overlay materials 5, 5, . . . and provided for the upper 3. However, the present invention is not limited to this embodiment. Specifically, as a variation which is an alternative to the embodiment in which the covering member 7 is provided for the upper 3, a fabric material-reinforcing structure for the fabric material 4 may be provided for the upper 3. The fabric material-reinforcing structure is comprised of a reinforcing material configured similarly to the overlay material 5 described above and increasing the mechanical strength of the fabric material 4, and a portion of the fabric material 4 to which the reinforcing material is bonded. This fabric material-reinforcing structure for the fabric material 4 is as effective as the covering member 7, and maintains the mechanical strength of the fabric material 4 constant. This makes it possible to reduce age deterioration of the fabric material 4, for example.

OTHER EMBODIMENTS

In the above embodiment, the mesh fabric is used as the fabric material 4. However, the present invention is not limited to this embodiment. Specifically, the fabric material 4 may be any stretchable material, such as a knitted fabric, a woven fabric, a nonwoven fabric, an artificial leather, or a cloth. The strain rate dependence of the covering member 7 of the upper 3 can be adjusted by taking account of the stretchability and stress properties of the fabric material 4 to be combined with the overlay material 5.

In the above embodiment, the overlay material 5 has a thickness within the range from 0.5 mm to 2.0 mm. However, the thickness is not limited to this range. For example, the thickness of the overlay material 5 may be set to be larger than 2.0 mm. As the thickness of the overlay material 5 increases, the stress with respect to the strain amount increases. Changing the thickness of the overlay material 5 as appropriate enables adjustment of the strain rate dependence of the covering member 7. This applies also to the thickness of the reinforcing material of the variation described above.

In the embodiment described above, the fabric material 4 is combined with the overlay material 5 by bonding the overlay 5 to the surface of the fabric material 4 via the extensible thermoplastic film material 6 (i.e., the hot-melt adhesive). However, the present invention is not limited to this embodiment. For example, the overlay material 5 may be combined with the fabric material 4 by, for example, fusion bonding through injection molding or hot pressing, adhesion with an adhesive, primer treatment, or fixing by sewing. This applies also to the process for combining the fabric material-reinforcing material of the variation described above with the fabric material 4.

In the embodiment described above, the covering members 7 are provided in portions of the upper 3 of the shoe S. However, the present invention is not limited to the embodiment. For example, a covering member 7 having the same structure as that of the upper 3 can be used for socks, gloves, tights (compression wear), brassieres, supporters, wear fitting the body, such as shirts and pants, gloves for baseball, wristbands, stocking bands, and the like. The fabric material-reinforcing structure for the fabric material 4 according to variation described above can also be used in these applications.

Note that the present invention is not limited to the embodiments described above, and various changes and modifications may be made without departing from the scope of the present invention.

Examples [Tensile Test 1]

First, the overlay material, which is one of the components constituting the covering member, was subjected to static and dynamic uniaxial tensile tests to confirm whether the overlay material had strain rate dependence.

For these tensile tests, a tensile tester called “ElectroPlus E 3000 electric tester” manufactured by Instron Japan Co., Ltd. was used at a high strain rate of 100%/s or more. As the main points of the specifications of this tensile tester, the dynamic load capacity is ±3000 N and the stroke is 60 mm. The tensile tester can perform static and dynamic tensile tests on various materials and the like. At low strain rates of 4%/s and 42%/s, a tensile tester called “3365-Type Electromechanical Universal Material Tester” manufactured by Instron Japan Co., Ltd. was used. The dynamic load capacity of the load cell of this tensile tester is ±1000 N. In addition, “ElectroPlus E 3000 electric tester” used for the test at the high strain rate was used also to make measurements at strain rates of 4%/s and 42%/s. It was confirmed that the same or similar measurement results were obtained by using the “3365-Ttype Electromechanical Universal Material Tester.”

Sample e3 made of an olefin-based thermoplastic elastomer and having a thickness of 2.0 mm was used as an example of this test. Sample e3 was prepared so as to have, at a portion set on the tensile tester, a length dimension (i.e. a dimension in the stretch direction of a mesh fabric which will be described later) of 4 cm, and a width dimension (i.e., a dimension in a direction intersecting with the stretch direction of the mesh fabric) of 2 cm.

Further, as a comparative example for Sample e3, Sample p1 made of soft polyurethane and having a thickness of 2.0 mm was used. Sample p1 was prepared so as to have the same size as that of Sample e3 made of the elastomer.

FIG. 6 shows the results (stress-strain characteristics) of the uniaxial tensile tests that were conducted on Sample p1 as the comparative example, using the tensile testers described above and at three different strain rates (i.e., 4.2%/s, 100%/s, and 500%/s). Likewise, FIG. 7 shows the results of the tensile tests conducted on Sample e3 as the example. Here, for the sake of convenience of discussion of results, a strain rate of 100%/s was defined as the “reference strain rate.” Based on this, a low strain rate region with strain rates equal to or lower than the reference strain rate (i.e., a strain rate region from 4%/s to 100%/s) was defined as the “low strain rate region,” whereas a strain rate region with strain rates higher than the reference strain rate was defined as the “high strain rate region.” The same applies to Tensile Test 2 which will be described later.

As shown in FIG. 6, for Sample p1 (i.e., the comparative example), the rate of change of the tensile stress values with respect to the strain amount was substantially constant, and no significant change was observed in the tensile stress values with respect to the strain amount irrespective of differences in the strain rate. That is, for Sample p1, the degree of stretch hardly changed in both the low and high strain rate regions. Thus, Sample p1 did not exhibit strain rate dependence.

In contrast, as shown in FIG. 7, for Sample e3 (i.e. the example), the relationship between the tensile stress and the strain amount varied so as to draw a nonlinear curve due to the viscoelasticity of the olefin-based thermoplastic elastomer. In particular, in the high strain rate region, the tensile stress value with respect to the strain amount tended to vary so as to draw a larger curve. For Sample e3, as the strain rate was increased from a low rate to a high rate, the tensile stress value with respect to the strain amount increased. For example, at the reference strain rate (100%/s) that is the upper limit of the low strain rate region, the tensile stress value was about 1.8 N/mm² with respect to a strain amount of 5%. On the other hand, at a strain rate of 500%/s included within the high strain rate region, the tensile stress value was about 2.9 N/mm² with respect to a strain amount of 5%. That is to say, in the low strain rate region, the tensile stress value with respect to a strain amount of 5% was relatively low, whereas in the high strain rate region, the tensile stress value with respect to a strain amount of 5% increased to be about 1.5 or more times as large as that in the low strain rate region.

As can be seen, it has been confirmed that the olefin-based thermoplastic elastomer has such characteristics that it is flexible and easy to stretch in the low strain rate region and is harder and less stretchable in the high strain rate region than in the low strain rate region. Thus, the olefin-based thermoplastic elastomer has strain rate dependence. It has become clear, from these results, that a covering member formed by combining an overlay material of the soft polyurethane with a fabric material does not exhibit strain rate dependence, whereas a covering member formed by combining an overlay material of the olefin-based thermoplastic elastomer with the fabric material exhibits strain rate dependence.

[Tensile Test 2]

Next, using the tensile testers described above, static and dynamic uniaxial tensile tests were carried out on Samples 1 to 12 of the covering member shown below, and based on the obtained results, the behavior of tensile load per unit width with respect to the strain rate (strain rate dependence) of each sample was observed. Here, in these tensile tests, the “tensile load per unit width” refers to a tensile load value (N/mm) applied to a unit width, where a direction intersecting with the stretch direction of the mesh fabric is defined as the width direction and a dimension of each sample in the width direction is converted to the unit width of 1 mm.

Four different mesh fabrics m1 to m4 produced by warp-knitting (i.e., double-raschel knitting) a polyester yarn were used as fabric materials for the samples. Each of these mesh fabrics was configured to stretch in the longitudinal direction of each sample described later. Further, the mesh fabrics m1 to m4 were different in degree of stretch, depending on the specifications (the yarn diameter, the coarseness of the stitches, the thickness of the fabric itself, etc.). The mesh fabrics m1 to m4 were designed so as to become less stretchable (harder) in the order from m1 to m4.

Olefin-based thermoplastic elastomers e1 to e3 were used as overlay materials to be bonded to the surfaces of the respective mesh fabrics. The elastomers e1 to e3 had different thicknesses. Specifically, the elastomer e1 had a thickness of 0.5 mm; the elastomer e2 had a thickness of 1.0 mm (i.e., the same thickness as that of the sample 2e used in Tensile Test 1 described above); and the elastomer e3 had a thickness of 2.0 mm.

Samples 1 to 12 of the covering members were prepared by appropriately combining the mesh fabrics m1 to m4 with the elastomers e1 to e3 (see Tables 1 to 12 for combinations of the mesh fabrics and the elastomers). The samples were prepared by using a method in which each elastomer was bonded to the surface of an associated one of the mesh fabrics via an extensible thermoplastic film material (i.e., a hot-melt adhesive). As shown in FIG. 8, each sample was prepared so as to have, at a portion set on the tensile testers described above (the portion defined by the dotted lines in FIG. 8), a length dimension of 4 cm in the stretch direction of the associated mesh fabric, and a width dimension of 2 cm in the width direction.

Uniaxial tensile tests were conducted on each of Samples 1 to 12 prepared in the foregoing manner, by using the tensile testers described above at four different strain rates (i.e., 4.2%/s, 42%/s, 100%/s, and 500%/s). Based on the test results (that is, the relationship between the strain and the tensile load per unit width), it was verified whether each sample had the strain rate dependence, and a study was conducted on appropriate ranges of the tensile load P per unit width (N/mm) with respect to the strain amount. Tables 1 to 4 show values of tensile load per unit width (N/mm) of Samples 1 to 12 at respective strain rates when the strain amount was 1%.

TABLE 1 Sample 1 Sample 2 Sample 3 (m1 + e1) (m1 + e2) (m1 + e3) Thickness of Thickness of Thickness of Elastomer = Elastomer = Elastomer = <Strain Amount = 1%> 0.5 mm 1.0 mm 2.0 mm Strain Rate  4.2%/s 0.05 N/mm 0.11 N/mm 0.34 N/mm  42%/s — — — 100%/s — — — 500%/s 0.65 N/mm 0.96 N/mm 1.35 N/mm

TABLE 2 Sample 4 Sample 5 Sample 6 (m2 + e1) (m2 + e2) (m2 + e3) Thickness of Thickness of Thickness of Elastomer = Elastomer = Elastomer = <Strain Amount = 1%> 0.5 mm 1.0 mm 2.0 mm Strain Rate  4.2%/s 0.11 N/mm 0.18 N/mm 0.32 N/mm  42%/s — 0.15 N/mm — 100%/s — 1.09 N/mm — 500%/s 0.71 N/mm 1.51 N/mm 1.87 N/mm

TABLE 3 Sample 7 Sample 8 Sample 9 (m3 + e1) (m3 + e2) (m3 + e3) Thickness of Thickness of Thickness of Elastomer = Elastomer = Elastomer = <Strain Amount = 1%> 0.5 mm 1.0 mm 2.0 mm Strain Rate  4.2%/s 0.12 N/mm 0.21 N/mm 0.39 N/mm  42%/s — — — 100%/s — — — 500%/s 0.76 N/mm 0.71 N/mm 2.20 N/mm

TABLE 4 Sample 10 Sample 11 Sample 12 (m4 + e1) (m4 + e2) (m4 + e3) Thickness of Thickness of Thickness of Elastomer = Elastomer = Elastomer = <Strain Amount = 1%> 0.5 mm 1.0 mm 2.0 mm Strain Rate  4.2%/s 0.34 N/mm 0.34 N/mm 0.46 N/mm  42%/s — — — 100%/s — — — 500%/s 1.13 N/mm 1.95 N/mm 2.47 N/mm

Tables 5 to 8 show values of tensile load per unit width (N/mm) of Samples 1 to 12 at respective strain rates when the strain amount was 5%.

TABLE 5 Sample 1 Sample 2 Sample 3 (m1 + e1) (m1 + e2) (m1 + e3) Thickness of Thickness of Thickness of Elastomer = Elastomer = Elastomer = <Strain Amount = 5%> 0.5 mm 1.0 mm 2.0 mm Strain Rate  4.2%/s 0.25 N/mm 0.31 N/mm 0.73 N/mm  42%/s — — — 100%/s — — — 500%/s 1.72 N/mm 3.51 N/mm 5.17 N/mm

TABLE 6 Sample 4 Sample 5 Sample 6 (m2 + e1) (m2 + e2) (m2 + e3) Thickness of Thickness of Thickness of Elastomer = Elastomer = Elastomer = <Strain Amount = 5%> 0.5 mm 1.0 mm 2.0 mm Strain Rate  4.2%/s 0.36 N/mm 0.56 N/mm 0.96 N/mm  42%/s — 1.04 N/mm — 100%/s — 2.05 N/mm — 500%/s 2.17 N/mm 4.41 N/mm 6.85 N/mm

TABLE 7 Sample 7 Sample 8 Sample 9 (m3 + e1) (m3 + e2) (m3 + e3) Thickness of Thickness of Thickness of Elastomer = Elastomer = Elastomer = <Strain Amount = 5%> 0.5 mm 1.0 mm 2.0 mm Strain Rate  4.2%/s 0.54 N/mm 0.72 N/mm 1.10 N/mm  42%/s — — — 100%/s — — — 500%/s 2.59 N/mm 4.06 N/mm 7.00 N/mm

TABLE 8 Sample 10 Sample 11 Sample 12 (m4 + e1) (m4 + e2) (m4 + e3) Thickness of Thickness of Thickness of Elastomer = Elastomer = Elastomer = <Strain Amount = 5%> 0.5 mm 1.0 mm 2.0 mm Strain Rate  4.2%/s 1.31 N/mm 1.59 N/mm 1.81 N/mm  42%/s — — — 100%/s — — — 500%/s 3.98 N/mm 5.79 N/mm 7.85 N/mm

FIGS. 9 to 11 and Tables 1 to 8 show that in Samples 1 to 12 for the covering member, each of which was formed by combining the respective overlay material of olefin-based thermoplastic elastomer with the surface of the respective fabric material, have such characteristics that they are flexible and easy to stretch in the low strain rate region whereas they are harder and less stretchable in the high strain rate region than in the low strain rate region.

Tables 1 to 4 show that the tensile load P per unit width (N/mm) with respect to a strain amount of 1% is within the range of 0.05≤P≤1.09 in the low strain rate region, whereas the tensile load P is within the range of 0.65≤P≤2.47 in the high strain rate region. Tables 5 to 8 show that the tensile load P per unit width (N/mm) with respect to a strain amount of 5% is within the range of 0.25≤P≤2.05 in the low strain rate region, whereas the tensile load P is within the range of 1.72≤P≤7.85 in the high strain rate region.

As a result of further consideration, it has been found that at a strain amount of 1%, the upper limit value (2.47 N/mm) of the tensile load per unit width in the high strain rate region is about twice as large as the upper limit value (1.09 N/mm) of the tensile load per unit width within the low strain rate region. Further, it has been found that at a strain amount of 5% (corresponding to an average strain amount generated when an external force is applied to the upper of known shoes), the upper limit value (7.85 N/mm) of the tensile load per unit width in the high strain rate region is about four times as large as the upper limit value (2.05 N/mm) of the tensile load per unit width in the low strain rate region. Based on these results, use of the samples of the covering member for the uppers of the sport shoes, for example, makes it possible to reliably obtain both the fitting property and the holding property described in the embodiment.

As described above, it has been concluded that the covering member of the present invention has such strain rate dependence that a tensile load per unit width with respect to a strain amount of the covering member is higher and the covering member is less stretchable when a strain rate of the covering member in the stretch direction of the fabric material is in a high strain rate region with strain rates above a reference strain rate than when the strain rate of the covering member is in a low strain rate region with strain rates at or below the reference strain rate. As to the fabric material-reinforcing structure according to the variation described above, the same or similar test results and conclusion as of the covering member can also be achieved.

INDUSTRIAL APPLICABILITY

The present invention is industrially applicable, for example, as a covering member for an upper of shoes for indoor sports in which a player makes sudden movements particularly frequently.

DESCRIPTION OF REFERENCE CHARACTERS

-   -   S: Shoe     -   1: Outsole     -   2: Midsole     -   3: Upper     -   4: Fabric Material     -   5: Overlay Material     -   6: Thermoplastic Film Material     -   7: Covering Member 

1. A covering member for covering a body, the covering member comprising: a stretchable fabric material; and an overlay material made of a thermoplastic elastomer and integrally provided on a surface of the fabric material, wherein a direction intersecting with a stretch direction of the fabric material is defined as a width direction, a strain rate region with strain rates higher than a reference strain rate is defined as a high strain rate region, a strain rate region with strain rates equal to or lower than the reference strain rate is defined as a low strain rate region, and the covering member has such strain rate dependence that a tensile load per unit width with respect to a strain amount of the covering member is higher and the covering member is less stretchable when a strain rate of the covering member in the stretch direction of the fabric material is in the high strain rate region than when the strain rate of the covering member is in the low strain rate region.
 2. The covering member of claim 1, wherein the overlay material is bonded to the surface of the fabric material via an extensible thermoplastic film material.
 3. The covering member of claim 1, wherein a relationship between the strain and the tensile load per unit width determined by a tensile test is that the tensile load P per unit width (N/mm) with respect to a strain amount of 1% is within the range of 0.05≤P≤1.09 in the low strain rate region, whereas the tensile load P is within the range of 0.65≤P≤2.47 in the high strain rate region.
 4. The covering member of claim 1, wherein a relationship between the strain and the tensile load per unit width determined by a tensile test is that the tensile load P per unit width (N/mm) with respect to a strain amount of 5% is within the range of 0.25≤P≤2.05 in the low strain rate region, whereas the tensile load P is within the range of 1.72≤P≤7.85 in the high strain rate region.
 5. A covering member for covering a body, the covering member comprising: a stretchable fabric material; and an overlay material made of a thermoplastic elastomer and integrally provided on a surface of the fabric material, wherein the covering member has such strain rate dependence that as a strain rate of the covering member in a stretch direction of the fabric material increases, a tensile load per unit width with respect to a strain amount increases and the covering member becomes less stretchable.
 6. A sport shoe comprising an upper having the covering member of claim
 1. 7. A fabric material-reinforcing structure comprising: a stretchable fabric material; and a reinforcing material made of a thermoplastic elastomer, integrally provided on the fabric material, and reinforcing a mechanical strength of the fabric material, wherein a direction intersecting with a stretch direction of the fabric material is defined as a width direction, a strain rate region with strain rates higher than a reference strain rate is defined as a high strain rate region, a strain rate region with strain rates equal to or lower than the reference strain rate is defined as a low strain rate region and the fabric material-reinforcing structure has such strain rate dependence that a tensile load per unit width with respect to a strain amount of the fabric material-reinforcing structure is higher and the fabric material-reinforcing structure is less stretchable when a strain rate of the fabric material-reinforcing structure in the stretch direction of the fabric material is in the high strain rate region than when the strain rate of the fabric material-reinforcing structure is in the low strain rate region.
 8. The fabric material-reinforcing structure of claim 7, wherein the reinforcing material is bonded to the surface of the fabric material via an extensible thermoplastic film material.
 9. The fabric material-reinforcing structure of claim 7, wherein a relationship between the strain and the tensile load per unit width determined by a tensile test is that the tensile load P per unit width (N/mm) with respect to a strain amount of 1% is within the range of 0.05≤P≤1.09 in the low strain rate region, whereas the tensile load P is within the range of 0.65≤P≤2.47 in the high strain rate region.
 10. The fabric material-reinforcing structure of claim 7, wherein a relationship between the strain and the tensile load per unit width determined by a tensile test is that the tensile load P per unit width (N/mm) with respect to a strain amount of 5% is within the range of 0.25≤P≤2.05 in the low strain rate region, whereas the tensile load P is within the range of 1.72≤P≤7.85 in the high strain rate region.
 11. A fabric material-reinforcing structure comprising: a stretchable fabric material; and a reinforcing material made of a thermoplastic elastomer, integrally provided on the fabric material, and reinforcing a mechanical strength of the fabric material, wherein the fabric material-reinforcing structure has such strain rate dependence that as a strain rate of the fabric material-reinforcing structure in the stretch direction of the fabric material increases, the tensile load per unit width with respect to the strain amount increases and the fabric material-reinforcing structure becomes less stretchable.
 12. A sport shoe comprising an upper including the fabric material-reinforcing structure of claim
 7. 